One scheme for isotope separation of uranium isotopes based upon photoexcitation of vibrational-rotational bands of uranium hexafluoride can make use of efficiently generated high intensity 16 micron infrared radiation. While gas dynamic lasers are available which provide 16 micron radiation, such as the HBr pumped CO.sub.2 laser, or TEA CO.sub.2 /SF.sub.6 laser, the search continues for efficient and powerful lasers operating in the 16 micron region for use in such applications.
One transition in CO.sub.2 gas with an energy difference corresponding to a 16 micron emission occurs between the 03'0 and 02.degree.0 energy levels. While CO.sub.2 has a number of vibrational-rotational levels to provide tunability, it may be desirable to increase the tunability through pressure broadening by operating the laser medium at relatively high pressures, typically approaching atmospheric pressure. Prior laser concepts have required operation at a relatively low pressure.
Where continuous or high pulse rate operation is desired, 02.degree.0 level bottlenecking due to stimulated emission or nonradiant transitions, even if some relaxation to the 01'0 level occurs, can reduce lasing efficiency.